1. Field of the Invention
The present invention relates to a method for the production of a paper-machine screen with a paper-side ply of weft threads and a run-side ply of weft threads.
2. Description of the Related Art
Paper-machine screens of this type serve, in paper-making, for receiving from a feed system a basic paper material which is generally in the form of a fiber suspension. This basic material is distributed over a large area on a paper-machine screen of this type or between two paper-machine screens of this type. During further manufacture, water can be extracted through the orifices of the fiber suspension which are present in such a screen. An essential requirement of such paper-machine screens is that a paper produced thereby reproduces as little as possible the fabric structure of the paper-side fabric ply. That is to say, a structure-free paper surface which is as smooth as possible.
A paper-machine screen of this type with two fabric plies is known from DE 42 29 828 A1. A paper-side fabric ply includes a paper-side ply of weft threads which are interwoven with warp threads of a first warp thread system assigned to the paper-side fabric ply. A second fabric ply includes run-side weft threads which are interwoven with the warp threads of a second warp thread system which are assigned to the run-side fabric ply. In order to ensure cohesion between these two fabric plies, there are binding weft threads, as they are known, which tie off alternately via warp threads of the run-side fabric ply and warp threads of the paper-side fabric ply. It would, of course, also be conceivable to use binding warp threads here, that is to say to provide a further warp thread system ensuring the mutual binding of the two fabric plies.
WO 02/00996 A1 discloses a paper-machine screen likewise with two plies of weft threads, to be precise a paper-side ply with somewhat thinner weft threads and a run-side ply with somewhat thicker weft threads. Two warp thread systems are provided such that the warp threads of one system and the warp threads of the other system are assigned to one another in each case in pairs, and these respective pairs of warp threads from two different warp thread systems alternate with one another when they are tied into or tied onto the run-side weft threads and paper-side weft threads, so that, on the one hand, a very fine fabric structure, for example with a linen weave, is obtained on the paper side, but, on the other hand, a connection of the two fabric plies is also at the same time achieved by means of these threads.